Input: psmouse - make sure we do not use stale methods

Several protocol initialization routines can fail after they set up
psmouse methods, such as reconnect and disconnect. This may lead to
these stale methods used with different protocol that they were
intended to be used for and may cause unpredictavle behavior and/or
crashes.

Make sure we start with a clean slate before executing each and every
protocol detection and/or initialization routine.

Reported-by: Paul Fox <pgf@laptop.org>
Acked-by: Tai-hwa Liang <avatar@sentelic.com>
Acked-by: Paul Fox <pgf@laptop.org>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>